Exhaust manifold and internal combustion engine comprising an exhaust manifold

ABSTRACT

An exhaust manifold assembly ( 40 ) including an exhaust manifold ( 17 ) that is at least partially surrounded by a cooling jacket ( 18 ) and combustion engine including such an exhaust manifold assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation patent application of International Application No. PCT/SE2004/000915 filed 11 Jun. 2004 which is published in English pursuant to Article 21(2) of the Patent Cooperation Treaty, and which claims priority to Swedish Application No. 03076916-0 filed 19 Jun. 2003. Said applications are expressly incorporated herein by reference in their entireties.

TECHNICAL FIELD OF THE INVENTION

The invention relates to an exhaust manifold of an internal combustion engine, and more particularly to an exhaust manifold that is provided with a cooling jacket.

BACKGROUND OF THE INVENTION

Marine propulsion systems are frequently mounted in environments sensitive to excessive heating. For this reason, exhaust manifolds and turbo units are frequently connected to a liquid coolant system.

As examples, U.S. Pat. No. 5,109,668 and U.S. Pat. No. 4,179,884 describe marine propulsion systems having exhaust manifolds that are surrounded by water jackets for safety reasons.

U.S. Pat. No. 4,977,741 describes an exhaust system combining an exhaust manifold and exhaust elbow, where the manifold is surrounded by a first water jacket and the elbow by a second water jacket. First and second water jackets are separated by a dam containing a passage for fluid communication between them. This will permit different temperature regions to be established in the exhaust system and prevent the formation of condensate due to excessive cooling of the exhaust gases.

In conventional applications, the coolant is recirculated to the coolant system from the cooling jacket of the exhaust manifold outside of the cylinder head by way of external channels. As a consequence, construction volume is increased and more space is required.

SUMMARY OF INVENTION

It is an object of this invention to avoid the above disadvantages and provide an exhaust manifold that allows a compact layout of a coolant system.

In existing engine coolant systems for engines provided with a liquid cooled exhaust manifold, a thermostat housing is provided for guiding the flow of the coolant medium either via a heat exchanger or directly to an inlet of a pump housing without intermediate cooling depending on the operating condition of the engine. The thermostat housing is normally arranged as a separate housing externally of the exhaust manifold.

This type of coolant system configuration having an external thermostat housing prevents compact design of the coolant system since it requires that the exhaust manifold cooling jacket be connected to coolant ducts leading to the thermostat housing, which coolant ducts are arranged externally of an engine block and a cylinder head sealing the cylinder block.

An exhaust manifold according to the invention is provided with a cooling jacket which includes a first exhaust manifold cooling jacket outlet, a second exhaust manifold cooling jacket outlet and a thermostat space at which a coolant outlet duct is forked into said first and second exhaust manifold cooling jacket outlets.

By including the thermostat housing in the exhaust manifold cooling jacket, the need for externally arranged thermostat housing is eliminated.

A particularly compact engine coolant system design is allowed by mounting exhaust manifold having an exhaust manifold cooling jacket according to the invention directly on a cylinder head provided with an integral cross over passage leading to a heat exchanger and an integral short circuit passage leading directly to a pump housing. In a coolant system using the suggested configuration, the total length of ducts arranged externally of the engine is substantially reduced whereby a compact design is achieved.

In a first embodiment of the invention, the coolant jacket includes a coolant inlet duct provided with a set of inlet openings arranged to be connected to a corresponding set of outlet ports arranged on a cylinder head.

In a second embodiment of the invention, the coolant inlet duct is provided with an outlet opening which is arranged to be connected to an inlet opening of coolant chamber arranged in a turbo charger assembly.

In a third embodiment of the invention, the exhaust manifold includes a set of exhaust inlet ducts arranged to form part of an exhaust outlet leading from a set of cylinders, wherein the set of inlet openings includes at least one inlet opening for each cylinder in the set of cylinders.

In a fourth embodiment of the invention, the exhaust manifold cooling jacket is divided by a partitioning wall into said coolant inlet duct and coolant outlet duct.

In a fifth embodiment of the invention, the coolant inlet duct and coolant outlet duct are flow connected via at least one bypass opening.

In a sixth embodiment of the invention, the exhaust manifold includes a set of exhaust inlet ducts, wherein at least one bypass opening is provided per exhaust inlet duct.

In a seventh embodiment of the invention, the coolant outlet duct have a larger cross section than said coolant inlet duct.

In an eighth embodiment of the invention, the coolant outlet duct of the exhaust manifold cooling jacket extends between an inlet opening and the first and second outlets of said exhaust manifold cooling jacket. The first cooling jacket outlet is arranged to be connected to the first port of the integral coolant cross over passage arranged in a cylinder head, the second cooling jacket outlet is arranged to be connected to a short circuit passage arranged in the cylinder head and the inlet opening of the coolant outlet duct is arranged to be connected to an outlet opening from a coolant chamber arranged in a turbo assembly.

The first, third, fourth, fifth, sixth and seventh embodiments all, separately and in combination, contribute to level out the temperature distribution within the exhaust manifold.

The second and eighths embodiments, separately and in combination, contribute to allow a compact design of a coolant system, when internal combustion engine is assembled using an exhaust manifold according to the invention.

In a most compact variant of the invention, the proposal is put forward that the coolant inlet duct be disposed above the coolant outlet duct.

A further object of the invention is to provide an internal combustion engine having a compact layout of the coolant system.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be discussed in greater detail with reference to the accompanying drawings wherein:

FIG. 1 is a perspective view of a cylinder head;

FIG. 2 is a partial cross-sectional view showing an internal combustion engine according to the invention, taken along line I-I in FIG. 3;

FIG. 3 is a partial cross-sectional view showing the engine taken along line II-II in FIG. 2;

FIG. 4 is a partial cross-sectional view showing an exhaust manifold assembly taken along line III-III in FIG. 3;

FIG. 5 is a partial cross-sectional view showing an exhaust manifold assembly in another variant of the invention, in a section as in FIG. 4;

FIG. 6 is a partial cross-sectional view depicting the engine shown in FIG. 3, with the exhaust gas manifold removed;

FIG. 7 is a partial cross-sectional view showing the exhaust manifold assembly in a section along line V-V in FIG. 4;

FIG. 8 is a partial cross-sectional view showing the exhaust manifold assembly in a section along line VI-VI in FIG. 7;

FIG. 9 is a partial cross-sectional view showing the exhaust manifold assembly in a view according to arrow VII in FIG. 8;

FIG. 10 is a partial cross-sectional view showing the exhaust manifold assembly in a section along line VIII-VIII in FIG. 8;

FIG. 11 is a partial cross-sectional view showing the engine in a section along line IX-IX in FIGS. 7 and 12; and

FIG. 12 is a partial cross-sectional view showing the engine in a section along line X-X in FIG. 11.

DETAILED DESCRIPTION

FIG. 1 show a perspective view of a cylinder head 1. The cylinder head 1 has a top face 1 a, a bottom face 1 b arranged to be connected to a cylinder block, a lateral exhaust flange face 1 c arranged to be connected to an exhaust manifold, a second lateral face 1 d being opposed to said lateral exhaust flange face 1 c, a front face 1 e and an end face 1 f.

The cylinder head 1 is provided with an integral coolant cross over passage 2 providing a first port 2 a for connection to a first exhaust manifold cooling jacket outlet and extending between said first port 2 a arranged at the lateral exhaust flange face 1 c and a first coolant outlet 2 b arranged at said second lateral face 1 d, which is an inlet flange face arranged to be connected to an intake manifold 7.

The cylinder head 1 is furthermore provided with an integral coolant short circuit passage 3 providing a second port 3 a for connection to a second exhaust manifold cooling jacket outlet and extending between said second port 3 a arranged at said lateral exhaust flange face 1 c and a second coolant outlet 3 b arranged at the bottom face 1 b for connection to a coolant pump inlet.

The cylinder head is provided with a coolant chamber 23 (see FIG. 2) extending along a length axis 4 of the cylinder head 1. The coolant chamber 23 is arranged for cooling a plurality of exhaust channels 5 a-5 h provided in the cylinder head 1. The lateral exhaust flange face 1 c is provided with at least one outlet port 6 a-6 d for each cylinder in said plurality of exhaust channels 5 a-5 h. The outlet ports 6 a-6 d are connected to said coolant chamber and are arranged to provide connections to a corresponding set of inlets arranged on an exhaust manifold cooling jacket.

The FIGS. 2-12 show an internal combustion engine 11 in which a cylinder head 1 as described in FIG. 1 is used. The internal combustion engine is provided with several cylinders 12 for reciprocating pistons 13. The engine 11 has a cylinder block 14 to which a cylinder head 1 is bolted. An exhaust manifold assembly 40 including an exhaust manifold 17 is flanged on to an exhaust flange face 1 c on the side of the cylinder head 1. The exhaust manifold 17 includes a set of exhaust inlet ducts arranged to form part of an exhaust outlet leading from a set of cylinders 12.

The exhaust manifold 17 is surrounded by a cooling jacket 18. The cooling jacket 18 is divided by a partitioning wall 19 in the flow direction of the exhaust stream into a coolant inlet duct 20 and a coolant outlet duct 21. The exhaust manifold 17 communicates with at least one exhaust port 41 per cylinder 12.

The coolant inlet duct 20 has a set of inlets 22 including at least one inlet 22 a-22 d per cylinder 12, which is flow-connected to the coolant chamber 23 of the cylinder head 1 via the outlet ports 6 a-6 d of the cylinder head 1.

The coolant inlet duct 20 leads from said set of inlets 22 to an outlet opening 20 a of said coolant inlet duct. The outlet opening 20 a of the coolant inlet duct 20 is connected to an inlet opening 27 to a coolant chamber 28 arranged in a turbo charger assembly 26.

The coolant outlet duct 21 extends between an inlet opening 21 a of said coolant outlet duct via a thermostat space 32 a at which the coolant outlet duct 21 is branched into a first and a second branch 21 b, 21 c provided with a first exhaust manifold cooling jacket outlet 21 d and a second exhaust manifold cooling jacket outlet 21 e.

The coolant inlet duct 20 is connected to the coolant outlet duct 21 via at least one bypass opening 24.

The exhaust manifold assembly 40 extends essentially along a longitudinal side of the cylinder head 1 between a front face 1 e and an end face 1 f.

In the region of the first end 31 of the exhaust manifold assembly 40, a thermostat space 32 a is provided for a heat control valve 32, which takes the coolant stream coming in from the coolant outlet duct 21, either via a coolant cross-over passage 2 situated in the area of the front face 1 e of the cylinder head 1 and the coolant outlet duct 35 to the heat exchanger 36 and, further on, to the coolant pump 37, or via a coolant short-circuiting passage 3 directly to the coolant pump 37. FIG. 7 shows the position of the control valve sliding sleeve 32 b when the engine is warm while FIG. 8 shows the position of the control valve sliding sleeve 32 b when the engine is cold. As indicated by arrows P1, in a hot engine the coolant will flow through the first exhaust manifold cooling jacket outlet 21 d forming an upper opening to the coolant cross-over passage 2. In a cold engine, however, the coolant passes through the second exhaust manifold cooling jacket outlet 21 e forming a lower opening of the exhaust manifold assembly 40 into the coolant short-circuiting passage 3 (see arrows P2 in FIGS. 8-12).

The exhaust manifold 17 is connected to the turbine part 25 of a water-cooled turbocharger 26 on the side of the second end 30 of the exhaust manifold assembly 40 in the area of the end face 1 f of the cylinder head 1. The coolant inlet 27 of the coolant chamber 28 of the turbocharger 26 is connected to the first coolant passage 20 of the exhaust manifold 17, the coolant outlet 29 to the second coolant passage 21 of the exhaust manifold 17.

The coolant flow is indicated schematically by arrows P1, P1.

The coolant will flow from cylinder coolant chambers 39 in the crankcase 14 into coolant chambers 23 in the cylinder head 1, from where it passes through inlets coolant chambers 23 in the cylinder head 1, from where it passes through inlets 22 into the first coolant passage 20, upon which the coolant stream is divided. The main stream in the first coolant passage 20, which is marked by full arrows P in FIG. 3, is passed to the turbine part 25 of the turbocharger 26, in the same flow direction as the exhaust gas in the exhaust manifold 17. The coolant stream flows through the coolant chambers 28 of the turbine part 25 of the turbocharger 26, and will reach the heat control valve 32 located at the front face 1 e of the cylinder head 1 via the second coolant passage 21, against the flow direction of the exhaust stream.

On the other hand, secondary streams of the coolant will reach the second coolant passage 21 directly from the first coolant passage 20, via bypass openings 24. These secondary streams are entered in FIG. 3 by broken arrows P1. Secondary streams P1 are controlled by predefined throttle cross-sections. Throttling may be achieved by providing precisely defined openings 24 a (see FIG. 4) in the partitioning wall 19, or by restricted cross-sections 24 b formed integral with the bypass openings 24, as shown in FIG. 5. With the aid of the secondary streams P1, a uniform temperature distribution will be obtained in the exhaust manifold assembly 40. In addition, excessive cooling of the turbine part 25 of the turbocharger 26 will be prevented.

In dependence of the temperature of the coolant, the heat control valve 32 will direct the coolant stream P to the coolant pump 37, either directly via a short-circuiting passage 38, or indirectly via a coolant cross-over passage 2. Once a certain, predefined coolant temperature is reached, the heat control valve 32 will open the flow path via the coolant cross-over passage 2 to a heat exchanger 36, in order to ensure sufficient cooling of the coolant. From the heat exchanger 36 the coolant will reach the coolant pump 37.

The coolant cross-over passage 2, which departs from the exhaust flange face 1 c and preferably extends to the inlet flange face 1 d of an inlet manifold not shown in the drawings, is positioned at the front face 1 e of the cylinder head 1, and, more preferably, cast integral therewith. The coolant short-circuiting passage 3 extending between the exhaust flange face 1 c and the cylinder head sealing face 1 d, is also cast integral with the cylinder head 1.

The assembly described herein will permit uniform cooling of the exhaust manifold assembly 40 in a simple and space-saving manner. 

1. An exhaust manifold assembly (40) comprising: an exhaust manifold (17) which is at least partially surrounded by a cooling jacket (18), wherein said cooling jacket (18) includes a first exhaust manifold cooling jacket outlet (21 d), a second exhaust manifold cooling jacket outlet (21 e) and a thermostat space (32 a) at which a coolant outlet duct (21) is forked into said first and second exhaust manifold cooling jacket outlets (21 d, 21 e); said exhaust manifold (17) includes a set of exhaust inlet ducts (17 a) arranged to form part of an exhaust outlet leading from a set of cylinders (12); and said coolant jacket (13) includes a coolant inlet duct (20) provided with a set of inlet openings (22 a-22 d) including at least one inlet opening (22 a-22 d) for each cylinder in said set of cylinders (12).
 2. The exhaust manifold assembly as recited in claim 1, wherein said set of inlet openings (22 a-22 d) are arranged to be connected to a corresponding set of outlet ports (6 a-6 d) arranged on a cylinder head (1).
 3. The exhaust manifold assembly as recited in claim 2, wherein said coolant inlet duct (20) is provided with an outlet opening (20 a) which is arranged to be connected to an inlet opening (27) of coolant chamber (28) arranged in a turbo charger assembly (28).
 4. The exhaust manifold assembly as recited in claim 2, wherein said exhaust manifold cooling jacket (18) is divided by a partitioning wall (19) into said coolant inlet duct (20) and a coolant outlet duct (21).
 5. The exhaust manifold assembly as recited in claim 4, wherein said coolant inlet duct (20) and coolant outlet duct (21) are flow connected via at least one bypass opening (24).
 6. The exhaust manifold assembly as recited in claim 5, wherein said exhaust manifold (17) includes a set of exhaust inlet ducts (17 a) in which at least one bypass opening (24) is provided per exhaust inlet duct (17 a).
 7. The exhaust manifold assembly as recited in claim 2, wherein said coolant outlet duct (21) has a larger cross section than said coolant inlet duct (20).
 8. The exhaust manifold assembly as recited in claim 1, wherein said coolant outlet duct (21) extends between an inlet opening (21 a) of said coolant outlet duct (21) and said first and second exhaust manifold cooling jacket outlets (21 d, 21 e).
 9. The exhaust manifold assembly as recited in claim 8, wherein said inlet opening of said coolant outlet duct (21) is arranged to be connected to an outlet opening (29) from a coolant chamber (28) arranged in a turbo charger assembly (26).
 10. An internal combustion engine (11) comprising: a cylinder block (14) having a plurality of cylinders (12), a cylinder head (1) sealing said cylinder block (14) and an exhaust manifold assembly (40); said exhaust manifold assembly (40) comprising an exhaust manifold (17) which is at least partially surrounded by a cooling jacket (18) that includes a first exhaust manifold cooling jacket outlet (21 d), a second exhaust manifold cooling jacket outlet (21 e) and a thermostat space (32 a) at which a coolant outlet duct (21) is forked into said first and second exhaust manifold cooling jacket outlets (21 d, 21 e); said exhaust manifold (17) includes a set of exhaust inlet ducts (17 a) forming part of an exhaust outlet leading from said plurality of cylinders (12); and said coolant jacket (18) includes a coolant inlet duct (20) provided with a set of inlet openings (22 a-22 d) that include at least one inlet opening (22 a-22 d) for each cylinder in said plurality of cylinders (12).
 11. The internal combustion engine as recited in claim 10, wherein said set of inlet openings (22 a-22 d) are connected to a corresponding set of outlet ports (6 a-6 d) arranged on said cylinder head (1).
 12. The internal combustion engine as recited in claim 11, wherein said coolant inlet duct (20) is provided with an outlet opening (20 a) connected to an inlet opening (27) to a coolant chamber (25) arranged in a turbo charger assembly (26).
 13. The internal combustion engine as recited in claim 11, wherein said exhaust manifold cooling jacket (18) is divided by a partitioning wall (19) into said coolant inlet duct (20) and coolant outlet duct (21).
 14. The internal combustion engine as recited in claim 11, wherein said coolant inlet duct (20) and coolant outlet duct (21) are flow connected via at least one bypass opening (24).
 15. The internal combustion engine as recited in claim 14, wherein said exhaust manifold (17) includes a set of exhaust inlet ducts (17 a) wherein at least one bypass (24) opening is provided per exhaust inlet duct (17 a).
 16. The internal combustion engine as recited in claim 11, wherein said coolant outlet duct (21) has a larger cross section than said coolant inlet duct (20).
 17. The internal combustion engine as recited in claim 10, wherein said coolant outlet duct (21) extends between an inlet opening (21 a) of said coolant outlet duct (21) and said first and second exhaust manifold cooling jacket outlets (21 d, 21 e).
 18. The internal combustion engine as recited in claim 17, wherein said inlet opening (21 a) of said coolant outlet duct (21) is connected to art outlet opening (29) from a coolant chamber (28) arranged in a turbo charger assembly (26).
 19. The internal combustion engine as recited in claim 11, wherein said cylinder head (1) includes a top face (1 a), a bottom face (1 b) connected to said cylinder block (14), a lateral exhaust flange face (1 c) connected to said exhaust manifold assembly (40), a second lateral face (1 d) being opposed to said lateral exhaust flange face (1 c), a front face (1 e) and an end face (1 f), said cylinder head (1) being provided with an integral coolant cross over passage (2) providing a first port (2 a) connected to said first exhaust manifold cooling jacket outlet (21 d) and extending between said first port (2 a) arranged at said lateral exhaust flange face (1 c) of said cylinder head (1) and a first coolant outlet duct (2 b) arranged at another of said faces (1 a, 1 b, 1 d, 1 e, 1 f).
 20. The internal combustion engine as recited in claim 19, wherein said first coolant outlet duct (2 b) is arranged on said second lateral face (1 d).
 21. The internal combustion engine as recited in claim 20, wherein said second lateral face (1 d) is an intake flange face connected to an intake manifold (7).
 22. The internal combustion engine as recited in claim 19, wherein said integral coolant cross over passage (2) is connected to a coolant pump (37) via a heat exchanger (36).
 23. The internal combustion engine as recited in claim 19, wherein said cylinder head (1) is provided with an integral coolant short circuit passage (3) providing a second port (3 a) connected to a second outlet (21 e) of said exhaust manifold cooling jacket (18) and extending between said second port (3 a) arranged at said lateral exhaust flange face (1 c) and a second coolant outlet duct (3 b) arranged at another of said faces (1 a, 1 b. 1 d, 1 e, 1 f) leading to a coolant pump (36) inlet.
 24. The internal combustion engine as recited in claim 23, wherein said second port (3 b) is provided at said bottom face (1 b).
 25. The internal combustion engine as recited in claim 19, wherein said cylinder head (1) is provided with a coolant chamber (23) arranged for cooling a plurality of exhaust channels (5 a-5 h) provided in said cylinder head (1), wherein said lateral exhaust flange face (1 c) is provided with at least one outlet port (6 a-6 d) for each cylinder in said plurality of cylinders (12), said outlet ports (6 a-6 d) being connected to said coolant chamber (23) and provide connections to a corresponding set of inlets (22 a-22 d) arranged on said exhaust manifold cooling jacket (18). 